DRAWINGS
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
FIG. 1 is a perspective view of a three phase electrical switching device illustrating the location of exemplary gas diverters with respect to the switching device in accordance with certain aspects of the invention;
FIG. 2 is a exploded perspective view of the contacting section of the three phase switching device of FIG. 1, in which the actuating section has been removed to illustrate the contact housing, two terminals, two splitter plate assemblies, and two gas diverters;
FIG. 3 is an exploded perspective view of the gas diverter and terminal of FIG. 2; illustrating the elements of the gas diverter in accordance with an exemplary embodiment;
FIG. 4 is an exploded perspective view of the gas diverter of FIG. 3; shown from the perspective of line 4-4, the terminal shown in FIG. 3 having been removed;
FIG. 5 is a sectional view of the three phase switching device of FIG. 1, sectioned along line 5-5, illustrating the relative location of the contacts, splitter plates, and gas diverter during the arc dissipation process;
FIG. 6 is a sectional view of the three phase switching device of FIG. 1, sectioned along line 6-6, illustrating the gas flow path through the gas diverter assemblies and the resultant increased length of the phase-to-phase short circuit path.
DETAILED DESCRIPTION
Turning now to the drawings, FIG. 1 illustrates an electrical switching device 10 in the form of a three-phase contactor for completing electrical current carrying paths for three separate phases 12 of electrical power. The switching device 10 includes an actuating section 14 and a contacting section 16 joined by fasteners 18. The actuating section contains the electromagnetic operator that mechanically opens and closes current carrying paths through the device. The operation and relevant internal components of the device will be discussed in more detail below. In general, however, each phase section 12 has an input or line terminal 20 and output or load terminal 22. Wire lugs 24 are secured to both the input and output terminals for receiving and completing an electrical connection with current-carrying wires or cables of a conventional design. Dividing panels or phase barriers 26 may be used to isolate vented gas from one phase from the neighboring phase. The phase barriers 26 are installed into slots 28 located in the contacting section 16. As will be discussed below, the invention allows the dividing panels to be reduced in size or possibly even eliminated, thereby reducing the required space needed to implement the switching device.
A gas diverter 30 is located at each terminal for both the input side 20 and output side 22. The gas diverter 30 slows, cools, and diverts the gas and plasma generated by the device before expelling it into the ambient environment, as discussed below.
FIG. 2 illustrates the contacting section 16 of the electrical switching device with the relevant parts of the contacting section exploded for explanatory purposes. The actuating section 14 (see FIG. 1) has been removed for clarity. Only two of the six terminals, splitter plate assemblies, and gas diverters are illustrated in FIG. 2. The contact housing 32 has an external wall 34 and is divided into three sections 36 by internal partitions 38. The partitions and walls serve to physically isolate the three phase sections from one another and the surrounding environment. The contact housing 32 has openings 40 in the exterior wall allowing the input and output terminals 20 and 22 to project outside of the housing. In the illustrated embodiment, the housing has channels 42 at each opening 40 configured to capture and orient the gas diverter 30 via a flange 44 extending from the diverter.
Each input terminal 20 and output terminal 22 has a bottom plate 46 used to mount the terminal to the contact housing 32. A stationary contact pad 48 is located on the terminal and serves as the stationary contact point that allows electrical current to flow through the device. When the switching device is opened, a turnback 50 directs the resulting electrical arc to a splitter plate assembly 52. The splitter plate assembly is configured with a plurality of splitter plates 54 that are stacked to allow the generated gas and plasma to flow therebetween. The gas and plasma enter the splitter plates on the entry side 56, flow to the exit side 58, and then into the gas diverter 30. The splitter plate assembly has an exterior wall 60 that engages a lip 62 on the terminal, locating the splitter plates over the stationary contact assembly.
The gas diverter 30 and exemplary terminal 20 are illustrated in an exploded view in FIG. 3. The gas diverter 30 has two mating housing elements, a first housing or front element 64 and a second element or housing 66. The front element 64 has an upper recess 68 and a lower recess 70. The housing has upper and lower panels 72 and 74 that enter into and mate with these recesses. Once the elements are joined, the panels and the wall of element 64 form a single solid flange 44 that positions and orients the gas diverter in the contact housing 32 via the channels 42. (See FIG. 2). The simple and effective flange channel mechanism allows for quick and easy installation of the gas diverter. Those skilled in the art will appreciate that there are a number of different mounting arrangements that could be used as alternatives to the particular construction illustrated. Partitions 76 extend from the back side of the front element 64 and form part of the flow path when mated with the housing 66, as described below.
In the view shown in FIG. 4, the terminal 20 has been removed and the gas diverter is viewed from the perspective of line 4-4 shown in FIG. 3. The opening 78 in the front element 64 serves as the gas inlet for the diverter 30. The housing 66 has exterior walls 80 that contain the gas and plasma with a further raised section 82 that provides for a gas exit. When the front element 64 is mated with the housing 66, the internal partitions 84 result in an upper flow path 86 and lower flow path 88. While the current embodiment provides for two flow paths, those skilled in the art will appreciate that the number and configuration of partitions 76 and internal partitions 84 could be varied to provide for more than two flow paths. Certain of the partitions could also be removed or configured to provide a single flow path, or flow paths that are otherwise configured.
The housing 66 is provided with an arcuate indention 90 allowing it to interface with mating features 91 in the terminal 20. The housing is not limited to this shape and can be configured to accommodate a number of different shapes and sizes.
In the current embodiment the housing elements are made from high temperature, arc resistant moldable plastic. Those skilled in the art will readily appreciate that the invention is not functionally limited to any specific material choices and any suitable material could be used for the housing elements. Furthermore, while the current design is a two piece assembly, alternative designs could include more than two pieces, or the diverter could be molded as a single piece, such as via the use of mold cores and so forth.
FIG. 5 is a partial sectional view of the switching device 10 from FIG. 1, sectioned along lines 5-5, illustrating the switching device opening and thereby causing a break in the current flow path. The switching device is opened when an electromechanical operator attached to the movable contact assembly 92 is released, typically by de-energization of an operator coil, and mechanically separates the movable contact pad 96 from the stationary contact pad 48, as indicated by reference numeral 94. This in turns interrupts the electrical current from flowing through the device, as indicated by arrow 98, and creates an electrical arc 100 between the two pads.
As discussed above, the arc produces significant heating through the release of electrical energy that is dissipated by the splitter plate assembly 52 as the arc is driven into the splitter plates. The turn back 50 and arc guide 102 typically direct the arc 104 to the splitter plates 54 magnetically, whereby the electrical energy is converted into thermal energy. Gases within the device may be ionized by the arc, creating plasma that is also driven towards the splitter plates. As a result of flow dynamics, the gas and plasma flow through the gaps 106 in the splitter plate assembly 52 and into either the upper 86 or lower section 88 of the gas diverter assembly 30 via the opening in the front element 64. The gas is contained within the gas diverter 30 by the exterior walls 80 and is directed in a specific direction with respect to the terminal 20.
FIG. 6 is a partial sectional view of the switching device 10 from FIG. 1, sectioned along lines 6-6, illustrating one of the gas flow paths through the diverter 30 for each respective phase section 12. The figure is exemplary of either the input side 20 or the output side 22 of the switching device 10 of FIG. 1. The figure illustrates three gas diverters 30 installed in the contact housing 32 via the flanges 44 and channels 42.
As discussed above, the gas and plasma enter the diverter 30 at the inlet 108 via the opening 78 in the front element 64. The partitions 76 extending from the front element 64 are interleaved with the internal partitions 84 contained in the housing 66 to form the flow paths 110. The flow paths 110 confine and divert the hot gas and plasma through a circuitous path, thereby slowing and cooling them before expelling the gas at the exit 112. The flow paths consist of generally parallel channels with 180 degree turnbacks on each respective end. Those skilled in the art will appreciate that a number of different configurations could be used to direct, divert and cool these gases and plasma. For example, a conical or spiral pattern or a variation of the parallel chambers could be used to create a number of different flow path configurations. Thus, the present invention is not functionally limited to any particular flow path arrangement. Furthermore, the gas flow for the current configuration is directed back towards the switching device 10 and thus away from possible temperature sensitive components and/or ignitable structures adjacent to the device. Those skilled in the art will appreciate that the flow may ultimately be directed back towards the switching device, or upwards, downwards, or away from the switching device. However, the illustrated embodiment enables released gas and any remaining plasma from each phase section to be effectively separated. Moreover, those skilled in the art will appreciate that the diverters achieve a very substantial effective length for cooling the gases and plasma, particularly as compared to known arrangement that simply release these into the immediate environment of the switching device. As noted above, in a present embodiment, flow paths are provided in upper and lower positions such that the flow of gas and plasma from the switching device is split between the upper and lower paths. Although not represented in FIG. 6, where provided, the upper flow path may be the same as, or as in a present embodiment, the opposite of the lower flow path. That is, while the lower flow path routes gas towards exit 112 on one side of the diverter, the upper flow path may route gas to an opposite side for venting.
Phase barriers 26 are shown in FIG. 6 for illustrative purposes. Those skilled in the art will appreciate that the phase-to-phase short circuit path has been significantly increased via the invention, as compared with prior art arrangements. That is, in known arrangements employing dividing panels alone, the phase-to-phase short circuit path is simply the length around the dividing panel, as indicated by arrow 114. Such arrangements, therefore, may require panels of substantial length. The gas diverter, on the other hand, creates a phase-to-phase short circuit path that is significantly increased and is a combination of the internal flow path 110 of the diverter plus the distance around the terminal 20 and phase barrier 26, as indicated by reference numeral 116. Depending upon the application, the significant increase in the short circuit path allows for the reduction in length of the dividing panels, or even their elimination altogether. As a result, the required space to implement the device and the overall length of the switching device package is reduced.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
Patent Application
20080074217
